1. The Field of the Invention
The present invention relates to a package for receiving an electronic part with a heat radiating structure having good heat radiating property, an electronic device using the same, and a mounting structure of the electronic device.
2. Description of Prior Art
In the related art, a package for receiving an electronic part such as semiconductor elements, generally includes a frame body formed of an electrical insulating material such as aluminum oxide sintered material, mullite sintered material, glass ceramic sintered material, and the like, a heat radiating plate formed of copper-tungsten material or copper-molybdenum material for effectively radiating heat generated from operation of the mounted electronic part to outside or into the air, and a cover body. The frame body is disposed on one main surface of the heat radiating plate so as to surround the mounting area of the electronic part. In addition, a plurality of wiring conductors made of tungsten, molybdenum, manganese, copper, silver, and the like, is adhered to the frame body and is derived from inside of the concave part, which is formed by the frame body and the heat radiating plate to the outer surface.
The electronic part is securely adhered to the mounting area of the one main surface of the heat radiating plate through an adhesive agent such as glass, resin, lead, and the like. Respective electrodes of the electronic part are electrically connected to the wiring conductors via bonding wires. Next, the cover body is joined to the frame body through a sealing material made of glass, resin, lead, and the like. The electronic part is received in a container consisting of the heat radiating plate, the frame body, and the cover body, to thus form an electronic device as a product. The electronic device may be mounted on an external heat radiating member by means of screw to further increase heat radiation efficiency.
The package for receiving the electronic part, having the heat radiating plate made of the copper-tungsten material or the copper-molybdenum material, has the heat radiating plate with high thermal conductivity. A coefficient of thermal expansion of the heat radiating plate approximates a coefficient of thermal expansion of silicon and gallium arsenide constituting the electronic part, or a ceramic material constituting the package. Thus, such a package is attracting attention as a package for receiving high exothermic electronic part such as a power IC or a high frequency transistor.
The related art is disclosed in Japanese Patent Laid-open No. H04-348062.
Recently, in response to the increased value of heat generated in accordance with high integration of the power IC or the high frequency transistor, the heat radiating plate is desired to have thermal conductivity value of 300 W/m·K or more. However, thermal conductivity of the conventional heat radiating plate consisting of the copper-tungsten material or the copper-molybdenum material is about 200 W/m·K, which is lower than the desired thermal conductivity. Therefore, the heat radiating property is becoming insufficient.
Meanwhile, thermal conductivity can be increased by raising content of copper in the copper-tungsten material or the copper-molybdenum material of the related art. Yet, in this case, difference of coefficients of thermal expansion between the electronic part and the heat radiating plate is increased and thus it is impossible to securely bond the electronic part onto the heat radiating plate.